1. Field of Invention
The present invention relates to a pump for propelling liquid through a flexible tube segment, and more particularly to a peristaltic pump for propelling liquid through the flexible tube in a concealed manner to ensure the purity of the liquid during transmission and to prevent an environmental pollution of the peristaltic pump.
2. Description of Related Arts
The peristaltic pump is commonly used as a safe and stable liquid pumping device in many different fields such as the medical, pharmaceutical, chemical, nuclear, aviation, and environmental industries.
Nowadays, conventional peristaltic pumps usually comprise an outer casing, a flexible pump tube which is adapted for allowing fluid to flow therealong, a plurality of rotating rollers spacedly supported at the outer casing at equal radial distance. The rotating rollers exert pressure on the pump tube thus to propel the liquid. A negative pressure will then be formed when the pump tube returns to it normal position so ask to suck in fluid from the source and thus continuously propel the fluid to travel in the pump tube. There are many disadvantages for such a conventional peristaltic pump. For examples, the peristaltic pump enclosed in China Patent CN85204827 and CN87107936 uses the rotating rollers to only exert pressure on the pump tube in a particular arc section of the guiding channel so as to achieve a more convenient installation of the pump tube. As a result, the design will experience a radial pulsing force on a particular section of the pump tube and also faces the following problems that are hard to overcome:
1. a high power motor is required to drive the machine to overcome the friction on the particular side, especially for the initial force and the torque, therefore it increases the size of the machine, i.e. the bigger size of driving shaft and the power of the motor, and the design has a low efficiency;
2. the machine is easy to wear out, a special design is needed to suit for the machine in order to keep a desired pressure and displacement exerted by the rollers on the pump tube; and
3. the machine is noisy.